Study: effective handwashing does not require hot water?

Handwashing is a hot topic in the world of food safety. Lack of proper handwashing procedures in foodservice and other sectors can lead to the spread of foodborne illness. Are current handwashing rules in need of updating? A new study suggests it may be time.

According to research released by Rutgers University, cool water is apparently just as effective as hot water in terms of washing away harmful bacteria. For the study, 21 volunteers had their hands covered with a harmless bacteria multiple times over a 6 month period. Each time, the volunteers were instructed to wash their hands at varying water temperatures—60 °, 79 ° or 100 °. They were also asked to use 0.5 ml, 1 ml or 2 ml volumes of soap.

“People need to feel comfortable when they are washing their hands but as far as effectiveness, this study shows us that the temperature of the water used didn’t matter,” says Donald Schaffner, professor and extension specialist in food science.

The water temperature does not make a difference in removing harmful bacteria, according to a Rutgers-New Brunswick study.

“This study may have significant implications towards water energy, since using cold water saves more energy than warm or hot water,” says Schaffner. “Also, we learned even washing for 10 seconds significantly removed bacteria from the hands.”

The study appears to indicate that there is no difference between washing hands with cold or hot water, nor does it matter how much soap is used. However, further study would help to decipher what types of soap are most effective at removing harmful bacteria from hands.

These findings are significant, particularly to the restaurant and food industry, because the U.S. Food and Drug Administration issues guidelines, every four years, to states. Those guidelines currently recommend that plumbing systems at food establishments and restaurants deliver water at 100 degrees Fahrenheit for handwashing.